Gustafsson, Linda

Abstract [en]

The discovery of microplastics (plastic particles smaller than 5 millimeters) in the world’s oceans has in the recent decade caused great concerns amongst scientists. These microplastics are widely distributed over the world’s oceans and have been found in sediments, along coasts, in the pelagic and in remote areas such as the poles. They derive from fragmented larger pieces of plastic and from industry and households wastewater. These particles are often mistaken by invertebrates as food and threatens the marine biota. The plastics are known to block the gut and intestines in the animal, which lead to a feeling of saturation. In the long run this could lead to starvation of the animal. In this study, examination has been done on blue mussels from the Swedish west coast, with the aim to discover the presence of microplastics in them. The blue mussels were diluted in nitric acid and sieved in mesh sizes of 0.07, 0.55 and 0.9 millimeters. Of 120 examined blue mussels 80 contained microplastics and in total 147 plastic particles were found. The particles consist of fibers and fragments in the colours black, blue, red and white/yellow/transparent. The fibers strongly dominated the samples and were found in all mesh sizes. The fragments were only found in the smallest mesh size and only in a few numbers. A correlation was found between the wet weight of the mussels and their plastic containment. This study shows distinct resemblance with earlier studies of Belgian and Canadian blue mussels in which fibers in different colours also dominated. Unfortunately it is almost impossible to ensure the source of the plastics only by visual comparisons, to do that further analysis will be needed. The problems associated with microplastics in blue mussels has been shown to be a lowered filtering activity and a lower uptake of nutrient, at the same time the mussels increase its energy consumption. In the end this leads to severe malnutrition. As the blue mussels make up an important base in the nutrient web the microplastics does not only have a negative impact to themselves, but also to many predators at higher trophic levels.